Method for producing a temperature-dependent resistor, and an electric temperature sensor

ABSTRACT

A method for producing a platinum-containing resistor, configured as a temperature sensor, includes applying a resistive coat to a ceramic support having a surface of electrically insulating material, covering an outer surface of the resistive coat with at least one layer of an electrically insulating material, which is preferably applied as a diffusion barrier in the form of an intermediate layer, and forming an electrode on the side of the resistive coat facing away from the substrate surface and spaced therefrom, using a thick-film technique. This electrode, comprising a layer of platinum, is covered by a glass passivation layer and is therefore surrounded by the electrically insulating material of the diffusion barrier and the glass passivation layer. The electrode is negatively electrically biased in relation to at least one connection of the resistive layer or the measuring resistor. An advantage is that platinum toxicants (Si- and metal ions), which are present in the form of positive ions in extreme ambient conditions, are attracted to the negative platinum layer.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of International Application PCT/EP99/04988, filed Jul. 14, 1999.

BACKGROUND OF THE INVENTION

[0002] The invention relates to a method for producing a temperature-dependent, platinum-containing resistor, configured as a temperature sensor, wherein a resistance layer is applied as a thick film on a substrate having a surface made of electrically insulating material. The outer surface of the resistance layer is covered by at least one layer made of an electrically insulating material which functions as a passivation layer and/or as a diffusion barrier. The invention also relates to an electric temperature sensor.

[0003] A rapid, platinum metal temperature sensor having a platinum resistance layer applied on a ceramic substrate and a passivation layer applied thereover is known from International Application publication WO 92/15101, wherein the passivation layer is constructed as a double layer made from a ceramic layer and a glass layer.

[0004] In order to manufacture such a temperature-dependent resistor as a temperature sensor, the resistance layer (Pt, meander structure) is applied as a thick film onto a substrate having a surface made of electrically insulating material, wherein the outer surface of the resistance layer is covered by a layer made of electrically insulating material, which functions as a passivation layer.

[0005] Furthermore, from European published patent application EP-A-0 543 413, a method is known for manufacturing a temperature-dependent, platinum-containing resistor configured as a temperature sensor, wherein an electrode is applied spaced from the resistance layer. An ion migration to the resistance layer, caused by current conduction, should thereby be avoided, and the electrode is connected electrically conducting with the resistance layer.

[0006] A method for manufacturing a temperature sensor is known from U.S. Pat. No. 5,202,665, wherein a platinum layer is applied on a substrate by thick-film technology. There, platinum powder is mixed with oxides and bonding agents and applied by screen printing; and then a tempering takes place in a temperature range between 1300 and 1350° C. A thus-produced temperature sensor having a platinum-containing layer on a substrate contains finely subdivided metallic platinum in an oxide ceramic and has a metallic platinum content in the range of 60 to 90 weight percent.

[0007] From European Patent EP 0 327 535 B1 a temperature sensor is known having a thin-film platinum resistance as a measuring element. A temperature measuring resistance made of platinum is formed on one surface of an electrically insulating substrate, wherein the resistance element is covered with a dielectric protective layer, which is preferably made of silicon dioxide and has a thickness in the range of 2000-4000 Angstroms. Furthermore, a diffusion barrier layer is provided as a cover layer, which is applied by deposition of titanium in an oxygen atmosphere to form titanium oxide. This barrier layer has a thickness in the range of 6000-12,000 Angstroms. Even if the diffusion barrier layer allows the admission of oxygen to the dielectric layer and thereby substantially prevents an attack of free metal ions released from the glass layer onto the platinum layer, under extreme environmental conditions it can nevertheless lead to an attack on the platinum layer, so that its physical behavior as a temperature measuring element is distorted.

[0008] Furthermore, an electric measuring resistor for resistance thermometers, as well as a method for producing such an electric measuring resistor, is known from U.S. Pat. No. 4,050,052 or the counterpart German Patent DE 25 27 739 C3.

SUMMARY OF THE INVENTION

[0009] An object of the invention is to protect the measuring resistor against external chemical or mechanical attacks and, in particular, to make certain that no sort of admission of contamination from the outside atmosphere into a platinum-containing resistance layer is possible.

[0010] The object of the invention is achieved in that, on the side of the resistance layer facing away from the substrate surface, an electrode is applied spaced from the resistance layer and is electrically insulated from the resistance layer by at least one layer of electrically insulating material.

[0011] It has proven to be especially advantageous that, on the one hand, a relatively reasonably priced manufacture is possible by applying a layer made of electrically insulating material as a diffusion barrier and/or as a passivation layer, while at the same time, because of the electrode preventing a contamination, a long service lifetime is obtained.

[0012] In a preferred embodiment, the resistance layer is applied onto a ceramic mass—preferably aluminum oxide—and then covered with a ceramic substance (likewise aluminum oxide) as a diffusion barrier or as a passivation layer. Here, the resistance layer can be applied on a fired ceramic substrate, whereby the advantage results that the geometry of the structure of the resistance layer remains unchanged. The diffusion barrier is preferably applied as an intermediate layer.

[0013] It is also possible, however, to apply the resistance layer onto a so-called “green” ceramic as a carrier, wherein after the application of the layer made of electrically insulating material as a passivation layer or as a diffusion barrier, this is sintered together with the carrier. Here, it is furthermore possible for a multiple layer system to also apply a laminated-on “green” ceramic as a diffusion barrier and/or as a passivation layer, which is then bonded to the carrier and resistance layer using a sintering process. For this, the use of an identical and/or similar material for carrier and covering of the resistance layer (passivation layer and/or diffusion barrier) proves to be especially advantageous, since a hermetically sealed embedding of the resistance layer and/or resistor structure is thereby possible.

[0014] In order to form the diffusion barrier and/or the passivation layer, ceramic powder can also be applied onto the resistance layer using a thick-film process and then sintered. An advantage that results therefrom is that this process is very cost-effective.

[0015] Furthermore, it is possible to apply ceramic powder onto the resistance layer of a fired substrate by a plasma spray process in order to form the diffusion barrier and/or the passivation layer. This has the advantage that the resulting layer, because of the high precipitation temperatures, also retains its stability at high temperatures that occur during later use.

[0016] In addition, it is possible to overglaze a plate made of ceramic as a diffusion barrier and/or as a passivation layer onto the resistance layer or to adhere it using a ceramic adhesive. Furthermore, the diffusion barrier and/or the passivation layer can be applied in a thin-film process using a PVD (Physical Vapor Deposition), IAD (Ion-Assisted Deposition), IBAD (Ion Beam-Assisted Deposition), PIAD (Plasma Ion-Assisted Deposition), or CVD (Chemical Vapor Deposition) magnetron sputtering process.

[0017] The electrode applied spaced from the resistance layer is preferably applied by a thick-film process, wherein it can be laid on by a screen-printing or stencil-printing process. This type of application proves to be advantageous by the structuring that results at the same time with the application. However, it is also possible to apply the electrode by a thin-film process.

[0018] The object of the invention is achieved with regard to the device for an electric temperature sensor with a platinum-containing resistance layer in thick-film technology, which is arranged as a measuring resistor provided with electrical contacts on an electrically insulating surface of a carrier constructed as ceramic substrate, wherein the resistance layer is covered with at least one layer made of an electrically insulating material for protection against contamination or damage, which material is constructed as a passivation layer and/or as a diffusion barrier, wherein on the side of the resistance layer facing away from the substrate surface, an electrode is applied spaced therefrom, wherein at least one part of a layer made of electrically insulating material is located between the electrode and the resistance layer.

[0019] The diffusion barrier is preferably constructed in the form of an intermediate layer. Proving to be advantageous are a cost-effective manufacture and a long servive lifetime of the temperature-dependent resistor. In one practical embodiment the thickness of the intermediate layer is in the range of about 0.2 μm to 50 μm.

[0020] The electrode is thus preferably arranged between the passivation layer and the intermediate layer. Furthermore, in one preferred embodiment, the electrode can be enclosed by the passivation layer. The electrode is preferably constructed as a platinum layer.

[0021] Furthermore, it is also possible to arrange the electrode on the side of the passivation layer facing away from the resistance layer. Here, the advantage results that the electrode, in the form of a platinum layer, protects the resistance layer from atmospheric poisoning in the sense of a “sacrificial electrode.”

[0022] In a further embodiment the electrode is provided with an electric connection. It is thereby possible to bias the electrode in an electrically negative manner against at least one connection of the resistance layer and/or the measuring resistor. It proves to be advantageous with an electrode in the form of a platinum layer that the platinum poisons (Si and metal ions), present as positive ions in extreme environmental conditions, are drawn to the negative platinum layer.

[0023] In one preferred embodiment according to the invention, the carrier is made of Al₂O₃. Furthermore, the diffusion barrier and/or the intermediate layer are also preferably made of Al₂O₃, MgO or a mixture of these two materials, wherein the weight percentage of Al₂O₃ lies in the range of about 20% to 70%. It is further possible to construct the diffusion barrier and/or the intermediate layer from a layer system with a layer sequence of at least two layers, which are formed respectively from at least one oxide selected from the group Al₂O₃, MgO, and Ta₂O₅. Here, at least one layer can be made from two of the oxides mentioned, wherein preferably a physical mixture of oxides is used. It is also possible, however, to use mixed oxides. In a further embodiment of the invention, the group of oxides consisting of Al₂O₃, MgO, Ta₂O₅ can be expanded to include hafnium oxide.

[0024] Preferably, the diffusion barrier and/or the passivation layer is made of a single-layer system according to Table 1 with the materials set forth in items 1 to 6 or of a multi-layer system according to Table 2, which has at least two layers 1 and 2, wherein however, on layer 2 one additional layer or several layers can be connected. The various layer materials are designated in the individual items or lines with the numbers 7 to 30. TABLE 1 Single Layer System 1 Al₂O₃ only 2 MgO only 3 Ta₂O₅ only 4 Mixture Al₂O₃/MgO 5 Mixture Al₂O₃/Ta₂O₅ 6 Mixture MgO/Ta₂O₅

[0025] TABLE 2 Multi-Layer System Layer 1 Layer 2  7 Al₂O₃ only Al₂O₃ only  8 Al₂O₃ only MgO only  9 MgO only MgO only 10 Ta₂O₅ only Ta₂O₅ only 11 Ta₂O₅ only Al₂O₃ only 12 Ta₂O₅ only 13 Mixture Al₂O₃/MgO Al₂O₃ only 14 Al₂O₃ only Mixture Al₂O₃/MgO 15 Mixture Al₂O₃/MgO Mixture Al₂O₃/MgO 16 Mixture Ta₂O₅/MgO Al₂O₃ only 17 Ta₂O₅ only Mixture Al₂O₃/MgO 18 Mixture Ta₂O₅/MgO Mixture Al₂O₃/MgO 19 Mixture Al₂O₃/Ta₂O₅ Al₂O₃ only 20 Al₂O₃ only Mixture Ta₂O₅/MgO 21 Mixture Al₂O₃/MgO Ta₂O₅ only 22 Ta₂O₅ only Mixture Al₂O₃/Ta₂O₅ 23 Al₂O₃ only Mixture Al₂O₃/Ta₂O₅ 24 Mixture Al₂O₃/MgO Mixture Ta₂O₅/MgO 25 Mixture Ta₂O₅/MgO Mixture Ta₂O₅/MgO 26 Mixture Al₂O₃/Ta₂O₅ Ta₂O₅ only 27 MgO only Mixture Al₂O₃/MgO 28 MgO only Mixture Al₂O₃/Ta₂O₅ 29 Mixture Al₂O₃/MgO MgO only 30 Mixture Al₂O₃/Ta₂O₅ MgO only

[0026] The use of these materials proves to be especially advantageous, since these metal oxides are also stable even at high temperatures. The intermediate layer and/or the passivation layer is preferably produced using a PVD, IAD, IBAD, PIAD, or magnetron sputtering process.

[0027] Furthermore, the passivation layer has, according to both embodiments, a mixture made of SiO₂, BaO and Al₂O₃, wherein the weight percentage of SiO₂ lies in the range of about 20% to 50%. Here, it proves to be advantageous that this mixture has a high insulation resistance.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0028] The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

[0029]FIG. 1 is a cross-sectional view along line A-A of the following FIG. 2 of one embodiment in which a platinum layer is provided on the diffusion barrier layer spaced from the resistance layer;

[0030]FIG. 2 is a schematic plan view of the embodiment of FIG. 1 with the two open contact surfaces and the contact for the electrodes;

[0031]FIG. 3 is a cross-sectional view of an embodiment similar to FIG. 1, wherein an additional passivation in the form of a ceramic plate is overglazed or adhered with ceramic adhesive;

[0032] FIGS. 4 to 6 show measuring resistors, which correspond in their principle construction to the prior art, but can contribute to a better understanding of the previously mentioned FIGS. 1 to 3.

[0033]FIG. 4 is a cross-sectional view of a measuring resistor with contact surfaces on a ceramic substrate, wherein the resistor is constructed as a meander structure and is covered by a diffusion barrier layer and a passivation layer;

[0034]FIG. 5 is a cross-sectional view of an embodiment similar to FIG. 4, wherein an additional passivation in the form of a ceramic plate is overglazed or adhered with a ceramic adhesive; and

[0035]FIG. 6 is a cross-sectional view of a measuring resistor with contact surfaces, whose meander-shaped resistor structure is hermetically embedded between the carrier and the covering, wherein this structure results from the sintering together of green ceramic.

DETAILED DESCRIPTION OF THE INVENTION

[0036] According to FIG. 1 the resistance layer 1, functioning as a measuring resistor made of platinum, is located on a flat surface of a substrate or carrier 2 made of aluminum oxide ceramic (Al₂O₃). It is preferably structured in the form of a meander with connection contact fields 5, 6, as known, for example, from the already mentioned German Patent DE 40 26 081 C1. The resistance layer 1 is surrounded on the side facing away from the substrate 2 by a diffusion barrier 10 as an intermediate layer, wherein this layer is in turn covered by an outer covering layer as a passivation layer 3 made of glass. Between the passivation layer 3 and the diffusion barrier 10 as an intermediate layer, an additional platinum layer is applied in a plane parallel to the plane of the carrier 2 as an electrode 4 spaced from the resistance layer 1, which should keep away from the resistance layer 1 any silicon ions, which may emerge from the passivation layer 3 made of glass, by absorbing the silicon ions. It is thus also possible in an aggressive high temperature environment to provide a protection against vagabond silicon ions dissolving from silicon dioxide compounds of the passivation layer 3, whereby a change that would otherwise occur in the resistor temperature curve of the measuring resistor is prevented by the previously deposited additional platinum layer as electrode 4. In this manner, the high temperature stability of the resistance layer 1 made of platinum, and thus of the entire temperature sensor, is maintained for a long measuring period.

[0037]FIG. 2 shows a plan view of FIG. 1 with the two connection surfaces 5, 6 for the resistor and a separate connection surface 7 for the electrode 4, which is depicted here along its circumference by heavy dashed lines for the purpose of a better overview. In this embodiment it is possible to bias the electrode “electrically negative” relative to the resistor. The elements that are poisonous to the resistor, such as Si and metal ions, are attracted to the negative electrode 4. A poisoning is thus prevented. Sufficient protection is already achieved, if the electrode is connected to the electrically negative connection of the resistor. The diffusion barrier 10 is depicted here along its circumference by a light dashed lines.

[0038]FIG. 3 shows the combination from FIG. 1 and the subsequently explained FIG. 5, wherein equivalent elements are maintained with the reference numerals used thus far. The additional plate 9 made of ceramic and adhered or glazed-on with an adhesive material 8 improves the corrosion resistance and represents an additional mechanical protection.

[0039] Even though according to FIG. 2 an approximately square resistor geometry is shown, the form of a resistor according to the invention lies in a range of about 2.4 to 6 mm for the width and in a range of about 10 to 100 mm for the length.

[0040] According to FIG. 4 the resistance layer 1, functioning as a measuring resistor, is located as a thick-film on a flat surface of a ceramic substrate 2, which is made of aluminum oxide. The resistance layer 1 is in the shape of a meander with connection contact surfaces 5, 6, as is known, for example, from German Patent DE 40 26 061 C1 or European Patent EP 0 471 138 B1. The connection contact surfaces are made of the same material as the resistance layer. The resistance layer 1 is provided, on its side facing away from the substrate, with a diffusion barrier layer as intermediate layer 10, which in turn is covered with a passivation layer 3 made of glass. Because of the glass passivation layer, the sensitive structure of the platinum-containing resistance layer 1 is effectively protected against atmospheric poisoning from the environment. In such a multi-layer construction the silicon ions, which are very harmful to the resistance layer 1 made of platinum, are held back. These silicon ions contaminate platinum very quickly by physical diffusion at high temperatures and thus drastically affect the temperature/resistor function of the platinum alloy resulting from it, so that the high temperature stability of the resistance layer 1 no longer results for temperature measurements.

[0041] Because of the first thermodynamically stable and pure aluminum oxide layer as an intermediate layer or diffusion barrier 10, the admission of silicon ions and other substances or ions that are poisonous for platinum is prevented. The resistance layer, which is structured for example in a meander shape, is thus protected from poisoning. The application of the intermediate layer or the diffusion barrier 10 can be achieved by physical vacuum metallization. The aluminum oxide layer is applied super-stoichiometrically in such a manner that a very stable layer of pure aluminum oxide (Al₂O₃) covers the platinum structure of the resistance layer 1. The silicon ion-containing passivation layer 3 made of glass thus does not make any contact whatsoever with the active platinum resistance layer, and a sealing of the resistance layer 1 as a mechanical protection against outside contaminating elements is thus ensured.

[0042] According to FIG. 5, the structure described in FIG. 4 is provided with an additional ceramic plate 9, which is glazed-on or adhered with ceramic adhesive. The ceramic plate represents an additional passivation and acts as a mechanical “protective shield” against abrasion by particles, as occur, for example, during use as a temperature sensor directly in the exhaust gas stream of combustion engines. The main function is the improvement of corrosion resistance. The bonding material is indicated with reference numeral 8. It is made of adhesive or glass.

[0043] According to FIG. 6 a resistor with connection contact surfaces 5, 6 is applied on a carrier 2 as a substrate made of green ceramic, and the structured resistance layer 1 is covered with a passivation layer, likewise made of green ceramic, in the form of a plate 9. By a common firing process, the carrier and covering are sintered together and hermetically embed the resistance layer or structure. After the sintering process, the carrier 2 and plate 9, as a covering, form a very stable mechanical and chemical passivation for the resistor with the properties of a “fired ceramic”. On the open connection surfaces 5, 6, connections in the form of wires, bands, or clamps can be welded, soldered or bonded, which can then be sealed with a ceramic adhesive or a glass.

[0044] The thickness of the resistance layer 1 lies in a range of about 5 to 50 μm, preferably about 15 μm. The thickness of the passivation layer 3 lies in a range of about 5 to 50 μm, preferably about 25 μm. The thickness of an electrode 4 applied by a thin-film process lies in a range of about 0.2 to 10 μm, preferably about 5 μm. The thickness of an electrode 4 applied by a thick-film process lies in a range of about 5 to 30 μm, preferably about 15 μm.

[0045] Supplementing the embodiment mentioned at the beginning, of the intermediate layer as a diffusion barrier 10, reference is made to the fact that this barrier is applied either by a thin-film process with a thickness in a range of about 0.2 to 10 μm, preferably about 5 μm, or by a thick-film process, with a thickness in a range of about 5 to 50 μm, preferably about 15 μm.

[0046] The thickness of the connection contact surfaces 5, 6 of the resistor 1 lie in a range of about 20 to 100 μm, preferably about 50 μm. These values also apply for the thickness of connection contact surface 7 of electrode 4. Carrier 2 has, as a substrate, a thickness in a range of about 0.13 mm to 1 mm, preferably about 0.635 mm.

[0047] The connection surfaces shown in cross-section in the figures are respectively arranged on opposite sides. It is however also possible to use embodiments of a temperature-dependent resistor according to the invention, in which the two connection surfaces are both arranged on one side.

[0048] The manufacture of a temperature sensor according to FIG. 1 is accomplished by the following process steps:

[0049] 1. Application of a platinum resistance layer 1 by a screen-printing process onto a carrier 2 constructed as a ceramic substrate, in a blank or multi-unit substrate.

[0050] 2. Application of the diffusion barrier 10 as an Al₂O₃ barrier layer using magnetron sputtering or plasma spraying. A coating of the connection contact surfaces 5, 6 is prevented by the use of resist masks.

[0051] 3. Adjusting the resistance value of the resistance layer 1 using laser-trimming.

[0052] 4. Application of an electrode 4 in the form of an accompanying additional platinum layer and the contact pad using screen printing or PVD or sputtering using resist masks.

[0053] 5. Application of the passivation layer 3 using screen printing.

[0054] 6. Separating the blank substrate or multi-unit substrate into individual resistance sensors by sawing.

[0055] It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims. 

We claim:
 1. A method for producing a platinum-containing, temperature-dependant resistor, configured as a temperature sensor, comprising applying a resistance layer (1) as a thick-film on a substrate having a surface made of electrically insulating material, covering an outer surface of the resistance layer (1) with at least one layer made of an electrically insulating material, which functions as a passivation layer (3) and/or as a diffusion barrier (10), and applying, an electrode (4) on a side of the resistance layer (1) facing away from the substrate surface and spaced from the resistance layer (1), the electrode (4) being electrically insulated from the resistance layer by the at least one layer of electrically insulating material.
 2. The method according to claim 1, wherein the electrode (4) is applied by a thick-film process.
 3. The method according to claim 2, wherein the electrode (4) is applied by a screen-printing process.
 4. The method according to claim 2, wherein the electrode (4) is applied by a stencil-printing process.
 5. The method according to claim 1, wherein the electrode (4) is applied by a thin-film process.
 6. The method according to claim 1, wherein the at least one layer of an electrically insulating material is applied as a diffusion barrier (10) in a form of an intermediate layer.
 7. The method according to claim 1, wherein the resistance layer (1) is applied to a ceramic mass, and is then covered with the at least one layer of electrically insulating material.
 8. The method according to claim 1, wherein the resistance layer (1) is applied to an already fired ceramic substrate as a carrier (2).
 9. The method according to claim 1, wherein the resistance layer (1) is applied on a “green” ceramic as a carrier (2), the at least one layer of electrically insulating material is applied as a ceramic mass, and the at least one layer of electrically insulating material is sintered together with the carrier.
 10. The method according to claim 1, wherein the at least one layer of electrically insulating material is applied as a laminated-on “green” ceramic and is then bonded to the carrier (2) and resistance layer (1) using a sintering process.
 11. The method according to claim 1, wherein in order to form the passivation layer (3) and/or diffusion barrier (10), the at least one layer of electrically insulating material is applied as a ceramic powder onto the resistance layer (1) using a thick-film process and is then sintered.
 12. The method according to claim 1, wherein in order to form the passivation layer (3) and/or diffusion barrier (10), the at least one layer of electrically insulating material is applied as a ceramic powder onto the resistance layer (1) using a plasma spray process.
 13. The method according to claim 1, wherein in order to form the passivation layer (3) and/or diffusion barrier (10), a plate (9) of electrically insulating material is glazed onto the resistance layer (1) or is adhered using ceramic adhesive.
 14. The method according to claim 13, wherein the plate (9) comprises ceramic.
 15. The method according to claim 1, wherein the at least one layer of electrically insulating material is applied as a passivation layer (3) and/or diffusion barrier (10) onto the resistance layer (1) in a form of a thin layer of ceramic.
 16. An electric temperature sensor comprising a platinum-containing resistance layer (1) made by thick-film technology, the resistance layer (1) being arranged as a measuring resistor provided with electrical contacts on an electrically insulating surface of a carrier (2) constructed as ceramic substrate, the resistance layer (1) being covered with at least one layer of an electrically insulating material for protection against contamination or damage, the at least one layer of electrically insulating material being constructed as a passivation layer (3) and/or as a diffusion barrier (10), and an electrode (4) applied on a side of the resistance layer (1) facing away from the carrier surface and spaced from the resistance layer (1), wherein at least one part of the layer of electrically insulating material is located between the electrode (4) and the resistance layer (1).
 17. The electric temperature sensor according to claim 16, wherein the diffusion barrier (10) has a form of an intermediate layer.
 18. The electric temperature sensor according to claim 17, wherein a thickness of the intermediate layer lies in a range of about 0.2 μm to 50 μm.
 19. The electric temperature sensor according to claim 16, wherein the electrode (4) is arranged between the passivation layer (3) as a covering layer and the intermediate layer as the diffusion barrier (10).
 20. The electric temperature sensor according to claim 16, wherein the electrode (4) is covered by the passivation layer (3).
 21. The electric temperature sensor according to claim 16, wherein the electrode (4) is arranged on a side of the passivation layer (3) facing away from the resistance layer (1).
 22. The electric temperature sensor according to claim 16, wherein the electrode (4) is provided with an external electric connection.
 23. The electric temperature sensor according to claim 16, wherein the electrode (4) is electrically negatively biased and/or has an electrically negative potential relative the resistance layer (1).
 24. The electric temperature sensor according to claim 16, wherein the electrode (4) has a form of a layer.
 25. The electric temperature sensor according to claim 16, wherein the electrode (4) comprises a platinum-containing layer.
 26. The electric temperature sensor according to claim 16, wherein the electrode (4) comprises platinum.
 27. The electric temperature sensor according to claim 16, wherein the carrier (2) comprises Al₂O₃.
 28. The electric temperature sensor according to claim 17, wherein the diffusion barrier (10) comprises Al₂O₃.
 29. The electric temperature sensor according to claim 17, wherein the diffusion barrier (10) comprises MgO.
 30. The electric temperature sensor according to claim 17, wherein the diffusion barrier (10) comprises tantalum oxide.
 31. The electric temperature sensor according to claim 17, wherein the diffusion barrier (10) comprises a mixture of Al₂O₃ and MgO having a weight percentage of Al₂O₃ in a range of about 20% to 70%.
 32. The electric temperature sensor according to claim 17, wherein the diffusion barrier (10) comprises a layer system having a layer sequence of at least two layers, respectively comprising at least one oxide selected from the group consisting of Al₂O₃, MgO, and Ta₂O₅.
 33. The electric temperature sensor according to claim 32, wherein at least one layer of the layer system comprises two oxides.
 34. The electric temperature sensor according to claim 17, wherein the diffusion barrier (10) is made by a magnetron sputtering process selected from the group consisting of PVD (Physical Vapor Deposition), IAD (Ion Assisted Deposition), IBAD (Ion Beam Assisted Deposition), PIAD (Plasma Ion Assisted Deposition), and CVD (Chemical Vapor Deposition).
 35. The electric temperature sensor according to claim 16, wherein the passivation layer (3) comprises a mixture of SiO₂, BaO and Al₂O₃ having a weight percentage of SiO₂ lying in a range of about 20% to 50%. 